In-vitro activities of 16 non-beta-lactam antibiotics against penicillin-susceptible and penicillin-resistant Streptococcus pneumoniae.

MICs of 16 non-beta-lactams were determined by agar dilution for 283 penicillin-susceptible, 122 intermediate and 23 fully penicillin-resistant isolates of pneumococci. Penicillin-resistant pneumococci were more likely to be resistant to tetracyclines, macrolides and related compounds. In the latter group, quinupristin/dalfopristin was the only compound whose activity was not influenced by penicillin resistance. Among the fluoroquinolones, clinafloxacin and trovafloxacin showed excellent activity. Strains resistant to macrolides, tetracycline and penicillin were concentrated in serogroups 6, 9, 14, 19 and 23.